This invention relates generally to gas turbine engines, and more particularly, to turbine nozzle assemblies for gas turbine engines.
Known gas turbine engines include combustors which ignite fuel-air mixtures that are channeled through a turbine nozzle assembly towards a turbine. At least some known turbine nozzle assemblies include a plurality of airfoil vanes that are coupled together such that the members are spaced apart. Within such nozzle assemblies, the airfoil vanes are coupled together by inner and outer band platforms which form a respective radially inner and outer flowpath boundaries. At least some known outer bands include a forward and an aft hook assembly that are used to couple the turbine nozzle within the engine.
Nozzle assemblies that include a plurality of airfoil vanes are generally more durable and experience less flow leakage in comparison to turbine nozzles including only one airfoil vane. Furthermore, such multi-vane turbine nozzles are generally cheaper to manufacture and assemble than turbine nozzles having only one airfoil vane. Because turbine nozzles may be subjected to high mechanical loads, at least some of such nozzle assemblies are assembled using brazing or welding operations. Specifically, the inner and outer band platforms are shaped using a grinder and are then brazed together to form the turbine nozzle assembly. However, because the grinding process may cause inconsistencies, accurately aligning the turbine nozzle vanes with respect to the turbine nozzle assembly may be difficult. For example, one member can be slightly angled with respect to the adjacent member, and such misalignment may cause variations in the throat areas between adjacent airfoil vanes which could adversely affect engine performance.